An example of a display comprising a vertical stack of at least two different color absorbing layers is disclosed in US2002/0171620. More precisely, US2002/0171620 relates to a transmissive color electrophoretic display incorporated with a backlight. The display has a plurality of laterally adjacent pixels. Each pixel is comprised of two or more cells which are vertically stacked, one directly above the other. Each cell in a stack also has laterally adjacent like cells which together form a layer of cells in the display. The cells contain a light-transmissive fluid and charged pigment particles that can absorb a portion of the visible spectrum, with each cell in a stack containing particles having a color different from the colors of the particles in the other cells in the stack. The color of a pixel is determined by the portion of the visible spectrum originating from the backlight that survives the cumulative effect of traversing each cell in the stack, hence the denotation color subtractive display. Suitable cell colors for the display in US2002/0171620 include cyan (C), magenta (M) and yellow (Y), yielding a three layer display. In CMY, magenta plus yellow produces red, magenta plus cyan makes blue and cyan plus yellow generates green. The amount and color of the light transmitted by each cell is controlled by the position and the color of the pigment particles within the cell. The position, in turn, is directed by the application of appropriate voltages to electrodes of the cell. When the pigment particles are positioned in the path of the light that enters the cell, the particles absorb a selected portion of this light and the remaining light is transmitted through the cell. When the pigment particles are substantially removed from the path of the light entering the cell, the light can pass through the cell and emerge without significant visible change. The color/spectrum of the light seen by the viewer, therefore, depends on the distribution of particles in each of the cells in the vertical stacks. Since each of the cells in the stack occupy the same lateral area as the pixel itself, the transmission efficiency can be significantly higher than that of solutions that rely on a side-by-side arrangement of subpixels to generate color.
However, a problem with the display disclosed in US2002/0171620 is that it may be difficult to manufacture because of the need to accurately vertically align individual pixels in the respective cell layers and the need to minimize the thickness of the intermediate light-transmissive windows to avoid color cross-talk between pixels.